The single most important fact about today's world is that the US is the only military superpower. The corollary to that is that there can be no effective peace enforcement action without the US in the middle of it.

We have seen, or heard, a heated argument between US Sen. Robert Dole and British Defense Secretary Malcolm Rifkind over blame for the present condition in Bosnia. Senator Dole blames the British because they resisted the use of NATO air forces against the Serbs closing in on the Bihac enclave. Mr. Rifkind says it ``ill becomes'' anyone who had not put his own ground troops into Bosnia to criticize those who have done so.

The essential fact behind both positions is that from the beginning of the Bosnia story the United States has been unwilling to do there what it was willing to do in the case of the invasion of Kuwait by Iraq.

Lawrence Eagleberger, who was undersecretary of state during the Bush administration, said on television Monday night that US intervention was considered and then rejected, at the beginning, because it would have involved putting major US ground forces into Bosnia. The figure 200,000 has been used for the probable number of US ground troops that would have been needed to play an effective role.

Morally and legally, Kuwait and Bosnia are similar cases. In both cases, an act of armed aggression was committed against a sovereign, independent, and recognized country. In the case of Kuwait, the US moved an army of more than 500,000 men from home bases to the Arabian peninsula and sent them into action against the armed invaders from Iraq.

In the case of Bosnia, the US declined to send its own ground troops against the aggressor.

The difference in US reaction in the two cases exposes the fact that the US intervened in the Gulf, not because Iraq had committed an act of armed aggression, which is prohibited under the UN Charter, but because Washington was worried about the flow of oil from the Gulf. That is, the US action in the Gulf was motivated by material self-interest, not by concern for the broader self-interest of maintaining law and order in the world.

Basis of peacekeeping

The UN was organized on the realistic basis that peacekeeping can be done only by the individual countries that possess significant military power. The peacekeeping function (which means the police role) is entrusted by the Charter to the Security Council, not to the General Assembly. There are five permanent members of the Security Council: the US, Russia, Britain, China, and France.

The selection of those five reflects the realities of military power at the time the UN was set up at the end of World War II. It would be realistic today to add Japan and Germany. This will probably happen in due time. Both are in fact major powers in today's world.

At one time there were two superpowers on that list of permanent members of the Security Council - the US and the Soviet Union. During that era, the UN could take only such effective action as had the support and participation, of both those superpowers.

Today Russia is no longer a superpower. It remains a substantial power, but it is no longer aggressive or expansionist. It is for the time being a relatively passive actor in world affairs.

When George Bush was president of the US at the time of the collapse of the Soviet Union, he declared the dawning of a ``new world order.''

If the phrase ``new world order'' meant anything, it meant a world in which the major powers would see to it that there would be no acts of military aggression upsetting world stability and doing damage to people and properties. Neither the invasion of Kuwait nor the war in Bosnia would be tolerated in a ``world order'' that is maintained by the leading members of the Security Council of the UN.

But now we have to add a new factor to the formula. There will be no policing of the ``new world order'' unless the US is ready and willing to play a central and active role.

US as European power

Some argue that the European nations could have resolved the Bosnia problem alone. This overlooks reality. The US, since World War I, has been a European power. Today it is the principal member of NATO. Others rely on the US, as the only superpower, for leadership.

Not everyone yet appreciates how novel is the present world condition.

To find anything at all similar in history we have to go back to the Roman Empire. For some 400 years the Western world was dominated by that single superpower. There was peace and stability throughout the ``known world.'' There has been many a nostalgic backward look toward those days through subsequent world history. The very establishment of the UN reflected a yearning for something similar to the era of stability that existed at the peak of the Roman Empire.

To say that the UN has been proved impotent in Bosnia is merely to recognize that the UN has no power in and of itself to enforce the peace and frustrate and punish aggressors. No world organization has power beyond that which will and can be provided by its powerful members. And these times are unique in that today there is only one superpower.

In Bosnia, the US wanted the aggression to be resisted by others. Undoubtedly had Washington chosen to take a leading role as it did in the Gulf, it could have organized an effective coalition of powers. The Serbian aggression could have been stopped at the outset and the horrors of the last three years could have been prevented. But the US, first under George Bush and then under Bill Clinton, declined to play the leading role.

It is now therefore an obvious and proven fact that as long as the US continues to be both the only superpower and at the same time a nonintervening superpower, there will continue to be tragedies like Bosnia.